CIRCULATION OF THE BLOOD 107 



other getting ruptured through the excessive charge of 

 blood, unless the blood should somehow find its way from 

 the arteries into the veins, and so return to the right side 

 of the heart, I began to think whether there might not 

 be a MOTION, AS IT WERE, IN A CIRCLE. Now, 

 this I afterwards found to be true; and I finally saw 

 that the blood, forced by the action of the left ventricle 

 into the arteries, was distributed to the body at large, and 

 its several parts, in the same manner as it is sent through ' 

 the lungs, impelled by the right ventricle into the pul- 

 monary artery, and that it then passed through the veins 

 and along the vena cava, and so round to the left ventricle 

 in the manner already indicated. This motion we may 

 be allowed to call circular, in the same way as Aristotle 

 says that the air and the rain emulate the circular motion 

 of the superior bodies; for the moist earth, warmed by the 

 sun, evaporates; the vapours drawn upwards are condensed, 

 and descending in the form of rain, moisten the earth 

 again. By this arrangement are generations of living 

 things produced; and in like manner are tempests and 

 meteors engendered by the circular motion, and by the 

 approach and recession of the sun. 



And similarly does it come to pass in the body, through 

 the motion of the blood, that the various parts are nour- 

 ished, cherished, quickened by the warmer, more perfect, 

 vaporous, spirituous, and, as I may say, alimentive blood; 

 which, on the other hand, owing to its contact with these 

 parts, becomes cooled, coagulated, and so to speak effete. 

 It then returns to its sovereign, the heart, as if to its 

 source, or to the inmost home of the body, there to re- 

 cover its state of excellence or perfection. Here it re- 

 news its fluidity, natural heat, and becomes powerful, fervid, 

 a kind of treasury of life, and impregnated with spirits, 

 it might be said with balsam. Thence it is again dispersed. 

 All this depends on the motion and action of the heart. 



The heart, consequently, is the beginning of life; the 

 sun of the microcosm, even as the sun in his turn might 

 well be designated the heart of the world; for it is the 

 heart by whose virtue and pulse the blood is moved, per- 

 fected, and made nutrient, and is preserved from cor- 



